Field of the Invention
The present invention relates to a polymer nanofiber structural body and a collecting apparatus using the structural body, and a method of producing the structural body.
Description of the Related Art
Industrial utilization of fine particles has become active. Meanwhile, a collecting apparatus (separator) for collecting fine particles scattered in air or dispersed in a liquid has been needed. In recent years, a polymer nanofiber structural body in which polymer nanofibers are integrated and three-dimensionally entangled with each other typified by a polymer nanofiber sheet has been attracting attention as a material for the collecting apparatus.
Unlike general fibers to be used in a nonwoven fabric and the like, each of the polymer nanofibers has a diameter of several microns or less. Accordingly, the polymer nanofiber structural body is drastically superior to a structural body including the general fibers because of the following reason. Even when the polymer nanofibers are integrated, an enormous specific surface area, a nanosize continuous pore structure, and a low density are obtained. Accordingly, new functions such as a mechanical strength, reactivity, electrical and optical characteristics, and the permeability of the inside of the structural body can be imparted. In particular, when the pore structure is utilized, a pore diameter of the order of submicrons is obtained and hence the pore structure is suitable for the collection of fine particles. Further, each of the polymer nanofibers uses an organic compound as a parent material and hence is lightweight. In addition, the polymer nanofibers can be produced with ease and at a low cost.
The polymer nanofibers are often used while being adhered to a support. However, the polymer nanofibers are porous and hence sufficient adhesiveness is not obtained at an interface with the support in some cases. When the adhesiveness between the polymer nanofibers and the support is bad, the polymer nanofibers may peel off the support upon rounding or bending of the polymer nanofibers together with the support at the time of the manufacture of the collecting apparatus. Japanese Patent Application Laid-Open No. 2012-219384 discloses a method involving mixing nanobeads at the time of the formation of the polymer nanofibers to improve the interfacial adhesiveness between the polymer nanofibers and the support.